The study aims at exploring the changes in the baroreflex induced by 3 noxious stimulation in anesthetized patients: tracheal intubation, tetanic stimulus, and surgical incision. Patients are randomly assigned to one of 2 groups: remifentanil-2 or remifentanil-4, corresponding to the target effect site concentration of this drug delivered through a TCI system. Other drugs included propofol and cisatracurium.